The problem is when a bigger capital think to "trap" these "smallest capitals", and make a big order in other direction (bull trap / bear trap).
TA has signals which can reveal those traps, too, and tools to try to minimize its effects (cut of losses, etc.)
This is the cause, that technical analisys is never 100% sure, and a normal trader / analyst never say you, that is sure price will go up / down...The correct affirmation is, that "we have 80% to price increase, but never can exclude the opposite"
And not only that, of course, but also which is the most likely appropriate reaction depending of the actual price movement.